1. Field of the Technology
The present disclosure is applicable to the application of lubricant such as oil to a fuser roll, in particular, to the uniform application of oil across a foam roll.
2. Description of the Prior Art
Electro-photographic processes such as that used in printers, copiers, and fax machines produce hardcopy images on a print media such as paper through precise deposition of toner onto the print media. The toner is applied by the print mechanism to correspond to the desired text or image to be produced. Such toner is then permanently affixed to the media by a fuser, which heats the toner such that it melts and bonds to the print media.
Typically, the fuser mechanism comprises at least two contiguous rollers, a hot roller and a backup roller. The media is transported to the print mechanism and passes between the contiguous rollers, such that fuser hot roller heats the media to melt and fuse the toner to the print media. As the toner melts, it becomes tacky and has a tendency to adhere to the fuser hot roller. Over time, toner accumulates on the hot roller, and eventually on the backup roller, causing degradation of the image quality on the print media.
Application of a lubricating substance to the surface of the fuser hot roller serves to weaken the bond between the toner and the hot roller and prevents accumulation of toner on the hot roller, and also serves to smooth the toner surface. Silicone oil is one such lubricating substance which has effective toner repelling properties. Alternatively, such oil can be applied to the backup roller, and then transferred to the fuser hot roller due to rotational association of the backup roller or other fuser roller with the fuser hot roller.
There are a variety of prior art oil delivery systems to apply lubricant to the fuser hot roller. Oil webs, oil wicking systems, and oil delivery rolls have been employed to provide a controlled supply of oil to the hot roller. For example, one prior art oil delivery system uses an oil web extending from a web supply roller to a web take-up roller. The web is generally a fabric material held in contact with the fuser hot roller by one or more biasing rollers. Oil delivery is controlled by indexing the web by controlled rotation of the take-up and supply rolls.
Another prior art oil delivery system utilizes a wicking element biased against the fuser hot roller by a spring loaded or other biasing member. The wicking element is a piece of fibrous textile or mesh material adapted to transport silicone oil through capillary action. The wicking element extends from an oil reservoir to the hot roller and delivers silicone oil along the length of the fuser hot roller.
Such prior art mechanisms, as shown in U.S. Pat. No. 6,434,357, however, often increase the complexity of the system by adding moving parts or increase maintenance. Further, as such oil delivery systems tend to promote a continuous oil flow, an idle period between printing cycles can result in a surge of oil, called an oil dump, during a successive print phase. Such oil dumps can compromise the finished print quality, and further can damage the printer if excess oil leaks onto other components.
Another prior art device, as shown in U.S. Pat. No. 6,434,357 shows a tank-type oil roller which uses a hollow support shaft as an oil reservoir. The hollow support shaft has oil delivery holes along the length for delivering oil to a metering material, such as rolled fabric, which is wrapped around the hollow support shaft. Such an oil delivery system, however, does not include a buffering and replacement sleeve and requires the entire system to be replaced for maintenance or replenishment, including the hollow core. This can be costly as well as time consuming.
It should also be noted that a spreader roll is often used in lubricating a fuser system. For example, U.S. Pat. No. 4,040,383 shows an apparatus for uniformly applying toner-release lubricant to, and for cleaning, heated fusing rolls used in copying or reproduction machines. The apparatus comprises a lubricant-dispensing roll containing an internal supply of lubricant; an applicator roll for transferring lubricant from the dispenser roll to the fuser roll and for wiping the fuser roll; and a spreader roll for evenly distributing the lubricant on the applicator roll prior to the completion of transfer to the fuser roll.
Also, in ink jet printing systems, water-based inks or phase-change inks are used to form images on media. Phase-change inks are solids, which are heated to form a liquid phase. The liquid phase ink is applied to a medium on which the ink solidifies to form images. Such ink jet printing apparatus can include a spreader roll and a pressure roll, which define a nip. These rolls apply heat and pressure to a printable medium, such as paper. The spreader spreads ink drops applied to the medium.
It would be beneficial, therefore, to develop a lubricant delivery system which reduces the number and complexity of moving parts and avoids undue maintenance and replacement of parts, while still providing a carefully metered supply of oil to the fuser or spreader roller.